Adjustable inductance device or the like



' Feb. 14, 1950 E. L. JOHNSON ADJUSTABLE INDUCTANCE DEVICE OR THE LIKE Filed Nov. 23, 1944 2 Sheets-Sheet 1 M /7 w E /9 24 25 30 7"" g p 3 Q Y. i\\ m 2 =21 L 3/ 2C 32 26 ATTORNEY ADJUSTABLE INDUCTANCE DEVICE OR THE. LIKE 2 Sheets-Sheet 2 Filed Nov. 23, 1944 INVENTOR Edh/ardZ.-]0/in5on BY fle ATTORNEY Patented Feb. 14, 1950 ADJUSTABLE INDUCTANCE DEVICE OR THE LIKE Edward L. Johnson, South Orange, N. J assignor to The Palnut Company, Irvington, N. J a corporation of New Jersey Application November 23, 1944, Serial No. 564,843

1 Claim. 1

This invention relates to inductance devices having one or more adjustable cores. Such devices are used, for example, in radio receivers as transformers, tuning coils and chokes.

Adjustment of the core may be utilized for such purposes as varying the value of the inductance, modifying the coupling in a transformer, or tuning a circuit in which the inductance is included. Usually it is necessary to make the final adjustment of the core or cores after assembly of the entire piece of equipment in which the inductance device is incorporated. It is also important that the adjustments be secure against vibration or accidental derangement, and at the same time provide for ready subsequent adjustment, that for any reason may become desirable.

Radio receiving sets and other so-called high frequency equipment are manufactured in great numbers; and therefore an important desideratum is that the parts be manufactured by methods of mass production, and be adapted to rapid assembly and adjustment, by relatively unskilled labor or even by automatic machines.

It is an object of this invention to simplify and improve the structure of adjustable core inductance devices by providing an insulating tube on which the coil or coils are wound or positioned, one or both ends of the tube being provided with a quick-attachable sheet metal fitment having screw-engaging means which firmly hold a magnetic core in adjustable position within the tube.

It is also an object to provide a sheet metal fitment for a tubular coil support, the fitment being quick-attachable to the tubular support and capable of firmly holding a magnetic core against vibration, lost motion, or accidental movement.

A further object is to provide an inductance device in which the tubular coil-support may be produced by simple and inexpensive automatic operations.

Further objects will be apparent from the following description.

It is to be understood that the terms used in the description and claim are to be given the broadest meaning consistent with their context and with the concept of my invention as distinguished from the pertinent prior art. For convenience, the device will at times be referred to as being in the position shown in the drawing, but it will be understood that the device can be used in any position and that the specification and claims are to be so understood.

Fig. 1 is a vertical section showing a twowinding two-core inductance device, such as a transformer, mounted upon a chassis plate or frame.

Fig. 2 is a vertical section, similar to Fig. 1, but showing the inductance device in a preliminary stage of assembly with respect tothe chassis plate or frame.

Fig. 3 is a horizontal section taken on the line 33 of Fig. 1.

Fig. 4. is a fragmentary vertical section of the lower portion of the mounted inductance device, the section being taken at the right angles to the sections of Figs. 1 and 2.

Fig. 5 is a perspective view showing the sheet metal fitment used at the lower end of the assembly shown in Fig. 1.

Fig. 6 is a top plan view, on an enlarged scale, of the sheet metal fitment used at the upper end of the assembly shown in Fig. 1.

Fig. '7 is an elevation, on an enlarged scale, of the sheet metal fitment shown in Fig. 6.

Fig. 8 is a bottom plan View, on an enlarged scale, of the sheet metal fitment shown in Figs. 6 and '7.

Fig. 9 is a fragmentary vertical section, on an enlarged scale, showing the upper sheet metal fitment and the upper portion of the coil tube, the parts being in position preliminary to assembly of the sheet metal fitment on the coil tube.

Fig. 10 is a fragmentary vertical section, on an enlarged scale, showing, among other things, the parts of Fig. 9 in assembled relation.

As shown more particularly in Figs. 1 and 2, the assembly includes a non-magnetic tube 10 of insulating material which acts as a support or form for a pair of coils or windings H and 12. The tube 10 may be a length cut from plain tubing manufactured in continuous or indeterminate length. Some of the tubing used at present is of fibrous material in the nature of impregnated paper, while other of the tubing is made of molded plastics or synthetic resins. The

coils H and I! may be either wound directly on the tube II], or they may be preformed and thentelescoped on the tube Hi and secured in place in any suitable manner.

Telescoped within the tube I0 are cores 1 la and [2a for the respective windings I! and i2. These cores are of magnetic material, such as molded iron powder, and they make a sliding fit with the interior of tube l0. Screw-threaded stems lib and 12b are affixed to the cores, as by the cores being molded onto the stems. These stems extend axially of the tube II) to a point substantially beyond the ends of the tube.

Stem IIb is threaded through a sheet metal fitment designated as a whole by He. This fitment is a one-piece sheet metal stamping of springy metal. I prefer to stamp the fitment from spring steel and harden and temper it after formation. Stem I2b is threaded into a metal fitment designated as a whole by I2c, the fitment I2c being also a one-piece sheet metal stamping of springy metal, e. g., spring steel hardened and tempered after formation.

Fitment IIc includes a metal annulus I5 (Figs. 6, 7, 8, 9 and which closely embraces the upper end of tube I0 and supports the tube against warping or distortion into out-of-round condition. Extending inwardly from annulus I5 is a convex disc-like portion I6 through which stem I Ib passes and with which stem I 6 makes screwthreaded engagement. This portion I6 is so stamped as to provide any suitable binding thread-engaging means for coacting with the threaded stem I ll), the binding engagement holding the stem against accidental or fortuitous rotation. Various types of binding thread-engaging means are known, some embodying separate friction means and others using female thread elements which themselves are of a binding type. I prefer to use binding female thread means, and the best form known to me is the form used in sheet metal nuts by The Palnut Company, of Irvington, N. J., and sold under the trade-mark of Palnut. As shown in the drawing, the sheet metal is so stamped as to provide a plurality (preferably four) of resilient fingers j which are so shaped and disposed as to enter the space between consecutive convolutions of a male thread. Fingers j resiliently bind or grip the male thread, and to this end the helix defined by the tips of the fingers is slightly undersize with respect to the male thread.

Depending from annulus I5 are oppositely positioned arms I! and I8 of arcuate cross section. At the annulus these arms are diametrically separated by a distance which will make a snug telescoping fit with the tube I0. As the arms leave the annulus, they converge so that before assembly of the fitment with the tube II], the body portion of the arms are separated by a lesser distance than the external diameter of the tube I0. To aid in telescopic assembly of the fitment on the tube I0, the arms I1 and I8 are flared outwardly at their free ends, as shown at I'Ia and I8a. The arm I8 is so stamped as to provide an inwardly extending projection or protuberance I9 which may correspond to the segment of a sphere. Tube I0 is drilled to provide two diametrically positioned duplicate holes I4, with either of which protuberance I8 may register when the fitment He is pressed home on tube Ill. Preferaby, the protuberance I9 and the hole I4 are so related in size that when the fitment I I0 is telescoped over the end of the tube II], with the protuberance I9 in proper rotative position, the protuberance will snap into and make snug circumferential fit with the hole l4, thereby holding the fitment I I 0 against any lost motion with respect to the tube I0.

It will be apparent that the core I la may be assembled with respect to the fitment I I0, and that then these thus-assembled parts can be assembled in simple telescopic fashion with the tube I 0. In such assembly, the arms I! and I8 are forced apart, with the result that after assembly these arms make resilient clasping engagement 4 with the outer wall of tube II), which engagement restrains the fitment II c in the assembled relationship.

The fitment I2c includes an annulus 20 which embraces the lower end of the tube I0 and supports it against distortion. Extending inwardly from annulus 20 is a convex disc-like portion 2I provided with binding screw-threaded means such as described in connection with fitment I I0. Extending upwardly from annulus 20 are oppositely positioned arcuate arms 22 and 23 which make clasping engagement with the side wall of tube I 0, after the fashion described in connection with arms I! and I8 of fitment IIc. Extending outwardly from the free ends of arms 22 and 23 are wings or flanges 24 and 25, one of which is provided with a downwardly extending finger 26. The wings or flanges 24 and 25 are, in unstressed condition, inclined downwardly as best seen in Figs. 2 and 5. Extending upwardly from annulus 20, and circumferentially interspersed with arms 22 and 23, are outwardlyinclined spring fingers 28 and 29. When the core I20. and its stem I22) have been assembled with respect to the fitment I20, these parts can be assembled in simple telescopic fashion with respect to the tube IIl.

The device is adapted to be mounted on a perforated sheet metal frame or plate 30, and for convenience I designate any such as a chassis plate. lhis plate 30 is provided with a hole, to telescopically receive the body of fitment I21: and with holes SI and 32, either of which may receive the finger 25. If desired, the entire inductance device may be assembled, before mounting, on the chassis plate. To mount the device, it is merely necessary to insert the body of the fitment I 20 through the receiving hole in the chassis plate, with the finger 25 in alignment witheither of the holes 3| and 32, and then press the assembly home. The fingers 28 and 29, after being forced inwardly and passing through the plate 30, snap outwardly and make latching engagement with the bottom of the plate 30, as best seen in Figs. 3 and 4.

On initial contact with the top of plate 30, flanges 24 and 25 are in the condition shown in Fig. 2, but are flexed upwardly as the assembly is pressed home so that the final assembly is approximately as appears in Fig. 1. This upward flexing of the wings 24 and 25 places further constricting force on the arms 22 and 23, so that they clasp the wall of the tube I0 with increased force after the fashion of a collet. Finger 26 prevents rotation of the assembly with respect to the plate 39. The initial downward inclination of wings 24 and 25 is sufificient to adapt the fitment for assembly with chassis plates 30 having a measure of variation in their thickness. Fig. 1 shows the inductance device mounted on a chassis plate of the maximum thickness for which the particular fitment I 20 is intended. When mounted on a' somewhat thinner plate, the flanges 24 and 25 will lie in position between that shown in Fig. 2 and that shown in Fig. 1.

I have disclosed the invention as applied to a transformer, or other inductance device having two windings and a core for each winding. It will be apparent, however, that various aspects of the invention are applicable to various specific inductance devices. It will also be apparent that the invention provides a simple and inexpensive construction whereby an inductance device having one or more coils or windings may be pro-. vided with adjustable cores and be readily mounted. The core adjustment may be readily made after complete assembly, by turning the stems lib and i212 with a screw driver or the like; and once the adjustment has been made, it remains fixed. The parts are readily removable for repair or replacement.

In compliance with the patent statutes I have disclosed the best form in which I have contemplated applying my invention, but it will be realized that the disclosure is illustrative and not limiting.

I claim:

For an inductance device in which a winding is positioned on the exterior of an insulating tube having a cylindrical terminal portion provided with a pair of diametrically-positioned cross axial holes and a magnetic core for the winding is telescoped into the tube in sliding fit relationship, a one-piece fitment of spring sheet metal, said fitment comprising: an annulus for closely embracing the terminal portion of the tube and circumferentially supporting it against distortion, a convex disc-like portion surrounded by the annulus, the disc-like portion being formed with an annular shoulder which aids in positioning the fitment on the tube and said disc-like portion having at its center binding female thread means, said thread means being resiliently cooperable with a threaded stem extending from the core to adjustably position the core lengthwise of the tube, and a pair of circumferentially-spaced oppositely-positioned arms of arcuate cross-section extending from the annulus in position to resiliently clasp the cylindrical side wall of the tube when the fitment is telescoped on the end of the tube, said arms having portions which in unstressed condition are diametrically spaced by a distance substantially less than the exterior diameter of the tube with which the fitment is to be assembled, said arms having flaring ends diametrically spaced apart by a distance greater than the exterior diameter of the tube, and one of said arms having an inwardly-extending protuberance to make snap engagement with either of said holes in the side wall of the tube to retain the fitment nonrotatable on the tube.

EDWARD L. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 822,099 Burnes May 29, 1906 832,723 Dowe Oct. 9, 1906 933,580 Preston Sept. 7, 1909 2,149,848 Lampel Mar. '7, 1939 2,258,652 James Oct. 14, 1941 2,335,205 Zepp Nov. 23, 1943 2,386,732 Wohlhieter Oct. 9, 1945 

